hi everyone, thanks for answering me in the topic before 5w-40 vs 10w-40. still i'am thinking shoul'd i stay with 10w-30 or switch to 5w-40 full synth or blend because of high miles on engine? my car have 245k on engine and manual says 5w-30, but that's to my opinion when the car has less miles. that's why i'am thinking to switch to 5w-40 for extra protection with this mileage, maybe i'am wrong, any answer/opinion is welcome.thanks....